The existence of deep-level defects in the band-gap of porous material was revealed by photo-induced current transient spectroscopy, combined with the results of thermovoltage and conductivity measurements. The defects were found to exhibit deep-donor levels in the upper part of the band-gap. It was found that the thermal emission and ionization energies of the defect increased, from 0.29 to 0.86eV below the conduction band edge, as the porosity increased. It was proposed that the defects played the role of luminescence killers.

Deep Level Defects in Porous Silicon W.H.Lee, C.Lee, Y.H.Kwon, C.Y.Hong, H.Y.Cho: Solid State Communications, 2000, 113[9], 519-22